Glyph Designer is a native OS X app that allows you to create bitmap fonts from TTF fonts. It generates both the texture atlas for the font as well as a font descriptor file which uses the BMFont format from AngelCode. The output can be used directly in Cocos2D using their CCLabelBMFont class as well as with Unity 3D plugins such as EZ GUI.

Glyph Designer allows you to apply a number of different effects such as solid and gradient fills, outlines and both inner and outer shadows. It also supports kerning and provides a preview feature that allows you to drag on an image from your game so you can see how the text will look in game without having to export the font and run the game.